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Articles 1 - 16 of 16
Full-Text Articles in Physics
Interaction Of Ultrashort-Laser Pulses With Induced Undercritical Plasmas In Fused Silica, Jeremy Gulley, Sebastian Winkler, William Dennis, Carl Liebig, Razvan Stoian
Interaction Of Ultrashort-Laser Pulses With Induced Undercritical Plasmas In Fused Silica, Jeremy Gulley, Sebastian Winkler, William Dennis, Carl Liebig, Razvan Stoian
Jeremy R. Gulley
Ultrafast light-material interactions near the damage threshold are often studied using postmortem analysis of damaged dielectric materials. Corresponding simulations of ultrashort pulse propagation through the material are frequently used to gain additional insight into the processes leading to such damage. However, comparison between such experimental and numerical results is often qualitative, and pulses near to but not exceeding the damage threshold leave no permanent changes in the material for postmortem analysis. In this article, a series of experiments is presented that measures the near- and far-field properties of a 140-fs laser pulse after propagation through a fused silica sample in …
Ultrafast Laser-Induced Damage And The Influence Of Spectral Effects, Jeremy Gulley
Ultrafast Laser-Induced Damage And The Influence Of Spectral Effects, Jeremy Gulley
Jeremy R. Gulley
Numerous studies have investigated the prerequisite role of photoionization in ultrafast laser-induced damage (LID) of bulk dielectrics. This study examines the role of spectral width and instantaneous laser frequency in LID using a frequency dependent multiphoton ionization (MPI) model and numerical simulation of initially 800 nm laser pulses propagating through fused silica. Assuming a band gap of 9 eV, MPI by an 800 nm field is a six-photon process, but when the instantaneous wavelength is greater than 827 nm an additional photon is required for photoionization, reducing the probability of the event by many orders of magnitude. Simulation results suggest …
Ultrashort Pulse Propagation And Multi-Chromatic Ionization In Dielectrics, Jeremy Gulley
Ultrashort Pulse Propagation And Multi-Chromatic Ionization In Dielectrics, Jeremy Gulley
Jeremy R. Gulley
No abstract is currently available.
Nonlinear Ultrashort Pulse Propagation And Multi-Chromatic Ionization In Bulk Dielectrics, Jeremy Gulley
Nonlinear Ultrashort Pulse Propagation And Multi-Chromatic Ionization In Bulk Dielectrics, Jeremy Gulley
Jeremy R. Gulley
No abstract is currently available.
Modeling Free-Carrier Absorption And Avalanching By Ultrashort Laser Pulses, Jeremy Gulley
Modeling Free-Carrier Absorption And Avalanching By Ultrashort Laser Pulses, Jeremy Gulley
Jeremy R. Gulley
In the past decade it was demonstrated experimentally that negatively-chirped laser pulses can lower the surface LIDT for wide band-gap materials by decreasing the number of photons required for photoionization on the leading edge of the pulse. Similarly, simulations have shown that positively-chirped pulses resulting from selffocusing and self-phase modulation in bulk dielectrics can alter the onset of laser-induced material modifications by increasing the number of photons required for photoionization on the leading edge of the pulse. However, the role of multi-chromatic effects in free-carrier absorption and avalanching has yet to be addressed. In this work a frequency-selective model of …
Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley
Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley
Jeremy R. Gulley
Numerous studies have investigated the role of photoionization in ultrafast laser-induced damage of bulk dielectrics. This study examines the role of spectral width and instantaneous laser frequency in laser-induced damage using a frequency dependent multiphoton ionization model and numerical simulation of an 800 nm laser pulse propagating through fused silica. When the individual photon wavelengths are greater than 827 nm, an additional photon is required for photoionization, reducing the probability of the event by many orders of magnitude. Simulation results suggest that this frequency dependence may significantly affect the processes of laser-induced damage and filamentation.
Ultrashort-Pulse Propagation Through Free-Carrier Plasmas, Jeremy Gulley, William Dennis
Ultrashort-Pulse Propagation Through Free-Carrier Plasmas, Jeremy Gulley, William Dennis
Jeremy R. Gulley
The past decade has seen frequent use of a modified nonlinear Schrödinger equation to describe ultrashort pulse propagation in materials where free-carrier plasmas are present. The optical contribution from the resulting free-current densities in this equation is often described using a classical Drude model. However, the ultimate form of this contribution in the modified nonlinear Schrödinger equation is somewhat inconsistent in the literature. We clarify this ambiguity by deriving the modified nonlinear Schrödinger equation from the classical wave equation containing a free-current density contribution. The Drude model is then used to obtain an expression for the complex free-carrier current density …
Simulation Of Ultrashort Laser Pulse Propagation And Plasma Generation In Nonlinear Media. Dissertation, Jeremy Gulley
Simulation Of Ultrashort Laser Pulse Propagation And Plasma Generation In Nonlinear Media. Dissertation, Jeremy Gulley
Jeremy R. Gulley
In this dissertation, a modified nonlinear Schrödinger equation is derived, which describes the propagation of ultrashort laser pulses through nonlinear materials in which plasma generation and laser-induced damage can occur. Differences between this model and models currently used in the literature are investigated and analyzed by numerical simulations. Ultrafast laser-induced material modification is investigated using this method by simulating the propagation of fully 3+1D (3 spatial plus 1 time dimension) laser pulses, which are numerically constructed from experimentally measured beam profiles and pulse shape data. The latest of these investigations reveals that standard rate-equation models for the free-electron plasma generation …
Material Damage From Ultrashort Bursts Of Light, Jeremy Gulley
Material Damage From Ultrashort Bursts Of Light, Jeremy Gulley
Jeremy R. Gulley
No abstract is currently available.
Simulation And Analysis Of Ultrafast-Laser-Pulse-Induced Plasma Generation In Fused Silica, Jeremy Gulley, Sebastian Winkler, W. M. Dennis
Simulation And Analysis Of Ultrafast-Laser-Pulse-Induced Plasma Generation In Fused Silica, Jeremy Gulley, Sebastian Winkler, W. M. Dennis
Jeremy R. Gulley
Recent experiments on optical damage by ultrashort laser pulses have demonstrated that the temporal pulse shape can dramatically influence plasma generation in fused silica. We use a modified 3+1D nonlinear Schrödinger equation for the pulse propagation coupled to a rate equation for the plasma density in the dielectric material to simulate pulse propagation and plasma formation in fused silica. We use these simulations to analyze the influence of pulse shape and beam geometry on the formation of the electron plasma and hence modification in the bulk material. In particular, we simulate the effect of pulses reconstructed from experimental data. It …
Modeling Plasma Induced Dispersion In A Nonlinear Schrödinger Equation, Jeremy Gulley, William Dennis
Modeling Plasma Induced Dispersion In A Nonlinear Schrödinger Equation, Jeremy Gulley, William Dennis
Jeremy R. Gulley
Ultrafast laser pulse propagation in dielectrics is often modeled by a modified nonlinear Schrödinger equation (NLSE). At laser intensities sufficient to cause ionization, a plasma term can be included in the modified NLSE to account for free-carrier optical effects. This term is linear in the field and may be calculated from the classical Drude theory. We explore the consequences of a newly developed method for including dispersion relations of the plasma term as predicted by the Drude theory into the framework of the modified NLSE. The plasma induced dispersion terms can be shown to strongly effect ultrashort pulse evolution through …
Simulation And Analysis Of Ultrafast Laser Pulse Induced Plasma Generation In Dielectric Materials, Jeremy Gulley, Sebastian Winkler, William Dennis
Simulation And Analysis Of Ultrafast Laser Pulse Induced Plasma Generation In Dielectric Materials, Jeremy Gulley, Sebastian Winkler, William Dennis
Jeremy R. Gulley
Recent experiments on optical damage by ultrashort laser pulses have demonstrated that the temporal pulseshape can dramatically influence plasma generation in fused silica and sapphire. In this work a modified 3+1D nonlinear Schroedinger equation for the pulse propagation coupled to a rate equation for the plasma density in the dielectric material is used to simulate pulse propagation and plasma formation in a range of dielectric materials. We use these simulations to analyze the influence of pulse-width, pulse-shape and beam geometry on the formation of the electron plasma and hence damage in the bulk material. In particular, when possible, we simulate …
Simulation Of Ultrashort Laser Pulses In Nonlinear Media, Jeremy Gulley
Simulation Of Ultrashort Laser Pulses In Nonlinear Media, Jeremy Gulley
Jeremy R. Gulley
No abstract is currently available.
Real-Time Measurements On Electron Plasma Response In Dielectrics Under Influence Of Ultrafast Laser Radiation, Sebastian Winkler, Jeremy Gulley, Igor Burakov, Razvan Stoian, Nadezhda Bulgakova, Anton Husakou, Alexandre Mermillod-Blondin, Arkadi Rosenfeld, David Ashkenasi, Ingolf Hertel, William Dennis
Real-Time Measurements On Electron Plasma Response In Dielectrics Under Influence Of Ultrafast Laser Radiation, Sebastian Winkler, Jeremy Gulley, Igor Burakov, Razvan Stoian, Nadezhda Bulgakova, Anton Husakou, Alexandre Mermillod-Blondin, Arkadi Rosenfeld, David Ashkenasi, Ingolf Hertel, William Dennis
Jeremy R. Gulley
No abstract is currently available.
Simulation Of Ultrashort Laser Pulse Propagation With High-Order Dispersion, Raman Scattering, And Shock Formation, Jeremy Gulley, Erik Zeek, William Dennis
Simulation Of Ultrashort Laser Pulse Propagation With High-Order Dispersion, Raman Scattering, And Shock Formation, Jeremy Gulley, Erik Zeek, William Dennis
Jeremy R. Gulley
No abstract is currently available.
Simulation Of High Intensity Laser Pulse Propagation Through Optical Systems, Jeremy Gulley, Erik Zeek, William Dennis
Simulation Of High Intensity Laser Pulse Propagation Through Optical Systems, Jeremy Gulley, Erik Zeek, William Dennis
Jeremy R. Gulley
No abstract is currently available.